Up to 2015, it was still relatively hard to get an ‘indie’ (bedroom/hobby coded game) onto a console.
The only exception being Android consoles (micro consoles), now just called AndroidTV boxes.

A while ago I found out about the Xbox One Dev Mode, which was launched in March 31 2016.
It basically turns any retail XBox One into a UWP device (Windows10) and you can target it via Visual Studio 2015 (community edition is free), Unity3D also has UWP support.

This feature, is still new, with UWP officially launching on XBox in 2017.
You need a DevCenter license (19USD once off) which lets you put apps on the Microsoft store.

When the XBox is in Dev Mode mode, it’s limited in memory and CPU’s it can use.